These will be available to you once the tutorial is complete, and you make your first dive into the open world.
Quests that progress the main story of the game are considered Main quests. Currently, the main quests lead you to tombs which house Wardens picked by The Betrayer to guard the imprisoned Gods.
These become available at the start of the game once you have completed the tutorial
Users will stumble across these when exploring and are highlighted right as you take your first dive. You can find them in Villages, completing them will award you with gold. That you can use to heal.
Adventure Quests are small pieces of content which gives a glimpse into the daily life of the inhabitants of Ávalt. They can be started in or nearby towns and only involve one enemy location, which the player must visit and complete to complete the quest.